Ferromagnetic exchange field stabilized antiferromagnetic ordering in a cuprate superconductor

TL;DR

This study demonstrates that a ferromagnetic exchange field can stabilize antiferromagnetic clusters within a cuprate superconductor, affecting its magnetic and superconducting properties.

Contribution

It provides experimental evidence of ferromagnetic exchange fields inducing antiferromagnetic clusters in a cuprate superconductor, revealing interplay between magnetism and superconductivity.

Findings

Ferromagnetic exchange field suppresses antiferromagnetic spin fluctuations.

Formation of short-range antiferromagnetic clusters observed.

Superconducting volume fraction decreases with cluster formation, showing quantum size effects.

Abstract

We report experimental evidence of formation of antiferromagnetic clusters in composites made of a cuprate superconductor La1.85Sr0.15CuO4 (LCu) and a ferromagnet La0.6Sr0.4CoO3 (LCo). From linear and non-linear ac-susceptibility measurement on this composite material it is found that the exchange field of LCo suppress the dynamic antiferromagnetic spin fluctuation of LCu and convert it into the short range ordered superparamagnetic type antiferromagnetic (AFM) clusters at the cost of superconducting volume fraction. These shrank superconducting volume fraction shows quantum size effect (QSE) and follows DeGennes-Tinkham theory on finite size effect of superconductor.